1. Field of the Invention
The invention relates to a battery charger and, more particularly, to a battery charger which can be enclosed into a casing of a main body by rotating an AC plug.
2. Description of the Related Arts
In recent years, a large variety of portable apparatuses including digital video cameras, digital still cameras, and the like have been accepted by various generations and widely used. Most of these portable apparatuses use batteries as power sources. Particularly, in recent years, with the advancement of battery technology, increase in recycling consciousness of the users, or the like, many portable apparatuses can be powered by chargeable batteries (for example, lithium-ion battery).
In accordance with an increase in demand for such a chargeable battery, many battery chargers for charging the battery by using an AC power source have been sold. Conventional battery chargers include a battery charger in which an AC plug can be enclosed in a charger main body (refer to JP-A-6-38388) and a battery charger having a contact member by which a charger main body and an AC plug can contact each other (refer to the Official Gazette of Japanese Utility Model Registration Application No. 5-88152). According to JP-A-6-38388, the AC plug is rotated around a rotary shaft, as a center, which penetrates a supporting portion for supporting two conductive blades which the AC plug has, so that the AC plug is projected by 90° from the main body of the charger and inserted into an outlet of an AC power source. In this case, the AC plug is rotated in the direction of plate surfaces of the two blades.
On the other hand, in a construction similar to that in which the AC plug is rotated around the rotary shaft, as a center, which penetrates the supporting portion for supporting the conductive blades, so that the AC plug is projected by 90° from the charger main body, there is a type in which the AC plug is rotated in the direction which perpendicularly crosses the plate surfaces of the two blades (what is called a lateral rotating type). In the present specification, a form of the rotation of the AC plug like such a lateral rotating type as mentioned above is called “lateral rotation”.
Examples of conventional battery chargers which belong to such a type are shown in FIGS. 1A, 1B, and 2. FIGS. 1A and 1B are a side elevational view (FIG. 1A) and a top view (FIG. 1B) showing a state where an AC plug which is inserted into an outlet of an AC power source is projected at an angle of about 90° to a casing of a battery charger.
FIG. 1A shows a state where an AC plug 51 having two conductive blades 52, an AC plug rotary shaft 53, and contact portions 54 which contact and are electrically connected to the conductive blades, which project at an almost right angle to a casing 50 of a battery charger. The AC plug 51 can be laterally rotated around the AC plug rotary shaft 53 as a center by about 90° in the direction of an arrow (d). By such a rotation, the AC plug 51 is enclosed into the casing 50. The contact portions 54 are arranged on the surface of the AC plug rotary shaft 53. The contact portions 54 are electrically connected to the corresponding conductive blades 52.
The contact portions 54 are arranged around an outer peripheral surface portion of the circular AC plug rotary shaft 53 so as to face each other while sandwiching a center point of the AC plug rotary shaft 53. In the state shown in FIG. 1A, the contact portions 54 contact two corresponding conductive spring terminals 55 and are electrically connected thereto.
When the AC plug 51 is rotated by about 90° in the direction of the arrow (d), the portion of the AC plug rotary shaft 53 is also similarly rotated in the direction of the arrow (d). Therefore, the contact portions 54 arranged on the surface of the AC plug rotary shaft 53 are also rotated in the direction of the arrow (d), so that the contact portion 54 is away from each corresponding conductive spring terminal 55 so as to keep a predetermined distance.
A contact state of the contact portions 54 and the conductive spring terminals 55 is more clearly illustrated in FIG. 1B. A cavity portion 56 is a space for enclosing the conductive blades 52 when the AC plug 51 is laterally rotated by about 90° in the direction of the arrow (d) in FIG. 1A.
FIG. 2 is a perspective view showing a portion around the AC plug 51 in the case where the AC plug 51 is in a state shown in FIGS. 1A and 1B as mentioned above, that is, a state where the blades 52 are projected at an almost right angle to the casing 50.
According to the battery charger of this type, as shown in FIG. 1A, the contact portions 54 of the poles are arranged on the same side of the surface of the AC plug rotary shaft 53 of the AC plug 51.
However, in the conventional battery charger, since the two contact portions are arranged only on one surface of the AC plug rotary shaft as mentioned above, one problem is that a distance between the two contact portions has to be set to a predetermined value or more in order to satisfy safety standards. According to UL (Underwriters Laboratories) 1310 as a safety standard, 6.4 mm or more has to be assured as a distance between the contact portions in this case.
Further, another problem of conventional battery chargers is that the rotary shaft portion of the AC plug and the conductive spring terminals have to be enlarged because the distance between the two contact portions is set to the predetermined value or more. Consequently, a predetermined space is necessary in the portion around the rotary shaft of the AC plug and the battery charger cannot be miniaturized.